This invention relates to a deadbolt assembly comprising a deadbolt and deadbolt actuating mechanism for a door, and more particularly to an improved device of this type which includes structure to prevent tampering.
Most door locks in current use are of one or the other of two types: the spring lock (or spring latch) or the deadbolt.
A spring lock is convenient to use. When one leaves a protected premises, such as a house, apartment, office or other protected building or suite, one sets the lock to the locked position and pulls the door shut on the way out. A spring-loaded latch engages a doorjamb and the door is locked. A major problem with spring locks is that they are relatively easily tampered with. This problem has long been recognized.
A deadbolt affords much greater security against unauthorized entry than a spring lock. It is less convenient, however. Typically, a key is required both to lock a door upon leaving and to unlock the door upon re-entry.
It is common practice to provide a door to a protected premises with both a spring lock and a deadbolt. These may be separate or may be combined into a single lock assembly.
A deadbolt installation in a door typically requires a recess in the door formed by a first bore (or cross bore) which extends from an outer face or surface of the door to an inner face or surface of the door and a second bore which intersects the first bore at right angles and extends to a door edge. A deadbolt reciprocates in this second bore. When extended, the deadbolt extends beyond the door edge to engage a doorjamb so that the door is locked. When retracted, the deadbolt is contained entirely within a cavity formed by the two bores. The deadbolt actuating mechanism is housed primarily within the first bore. The first bore is typically either 1 xc2xdxe2x80x3 or 2 xe2x85x9xe2x80x3 in diameter. A door recess of the same configuration and dimensions may be used for housing a combined spring latch and deadbolt lock assembly.
While a deadbolt is much more secure than a spring lock, it is not entirely immune to tampering. A primary purpose of the present invention is to afford greater protection against tampering than has been realized heretofore.
This invention provides a deadbolt assembly for a door in which the assembly comprises first and second housing members which are adapted to be disposed in proximity with an outside face and an inside face, respectively, of a door. A deadbolt is provided which is reciprocable between an extended (or latching) position and a retracted (or unlatching) position. A deadbolt actuating mechanism is disposed in a cavity in the door between the first and second housing members for reciprocating the deadbolt. This invention further comprises, as novel tamper-inhibiting members, a pair of oppositely oriented generally cylindrical shells surrounding the deadbolt actuating mechanism for preventing tampering with the mechanism. Each shell comprises a ring at a first end and a protective structure which extends axially in one direction from the ring. This direction is transverse to the direction of reciprocation of the deadbolt. The ring and the protective structure encircle the deadbolt actuating mechanism. The ring of each shell is in proximity with one housing member and the protective structure extends toward the other housing member. An opening in the protective structure permits linking of the deadbolt actuating mechanism so as to permit reciprocatory movement of the deadbolt without interfering with the shells, while inhibiting tampering with the deadbolt mechanism.